Structure and formation of highly luminescent protein-stabilized gold clusters.

Highly luminescent gold clusters simultaneously synthesized and stabilized by protein molecules represent a remarkable category of nanoscale materials with promising applications in bionanotechnology as sensors. Nevertheless, the atomic structure and luminescence mechanism of these gold clusters are still unknown after several years of developments. Herein, we report findings on the structure, luminescence and biomolecular self-assembly of gold clusters stabilized by the large globular protein, bovine serum albumin. We highlight the surprising identification of interlocked gold-thiolate rings as the main gold structural unit. Importantly, such gold clusters are in a rigidified state within the protein scaffold, offering an explanation for their highly luminescent character. Combined free-standing cluster synthesis (without protecting protein scaffold) with rigidifying and un-rigidifying experiments, were designed to further verify the luminescence mechanism and gold atomic structure within the protein. Finally, the biomolecular self-assembly process of the protein-stabilized gold clusters was elucidated by time-dependent X-ray absorption spectroscopy measurements and density functional theory calculations.

Endovascular management of peripheral vascular trauma.

Endovascular interventions (EVIs) are an important adjunct to open surgical management of peripheral vascular injuries. In appropriate situations, EVIs decrease operative time, estimated blood loss, and iatrogenic complications when compared with similar surgical cohorts by limiting surgical dissection in traumatized operative fields. In situations where definitive repair is not possible with EVIs, endovascular techniques permit control of hemorrhage or damage and facilitate open surgical repair. EVIs for peripheral vascular injury have proven effective in three anatomic regions: the neck, subclavian, and lower-extremity regions. The interventional radiologist should become familiar with the physical and personnel resources in the area preferred by the consulting trauma team to minimize unnecessary delays when acute intervention or angiography is requested. Clinical and radiographic surveillance for patency and compliance with antiplatelet or anticoagulation therapy is essential but has historically been poor in trauma patients.

Endovascular versus open management of blunt traumatic aortic disruption at two military trauma centers: comparison of in-hospital variables.

BACKGROUND: Blunt traumatic aortic disruption (BTAD) carries significant mortality and morbidity. Traditional open repair has appreciable risks of perioperative mortality and spinal cord ischemic complications. Endovascular repair may reduce the incidence of these adverse outcomes. We present the experience at two military trauma centers with thoracic aortic endografting for trauma (TAET) and compare this with recent open experience. METHODS: A review of inpatient records was performed. All patients undergoing open repair or TAET for acute BTAD were studied. Collected data included demographics, injury characteristics, and in-hospital variables. Descriptive statistics were calculated with two-tailed t-tests performed for comparison of continuous variables. RESULTS: Five open and eight TAET repairs were performed. Mean age was 32 years (range 28-50) in the TAET group and 35 (25-57) in the open group. All patients, except one TAET, had at least one associated injury with thoracic injuries predominating. Twelve BTAD were just distal to the left subclavian artery. One injury, treated with TAET, was just proximal to the celiac. Operative blood loss averaged 298 +/- 394 mL in the TAET group vs. 2,400 +/- 3,800 mL in the open group (p = 0.18). Crystalloid infusions were similarly reduced in TAET patients, 1,019 +/- 532 mL vs. 4,860 +/- 1,547 mL, p < 0.05), as were red blood cell transfusions, 1.6 units vs. 5.0 units (p = 0.12). The majority of patients [6/8 (75%) TAET, 5/5 (100%) open] experienced an inpatient complication (p = 0.09). All open patients had at least one infectious complication. There were no inpatient deaths related to aortic injury or spinal cord ischemic complications. CONCLUSIONS: TAET is feasible for the treatment of BTAD in military trauma centers. It is important for military centers to accomplish this with adequate results as endovascular technologies are now being taken to the battlefield. Decreased blood loss and resuscitation requirements compared to open repair are likely contributors to improved outcomes with TAET.

Neutron activation analysis for Dy, Hf, Rb, Sc and Se in some Ghanaian cereals and vegetables using short-lived nuclides and Compton suppression spectrometry.

A pseudo-cyclic instrumental neutron activation analysis (PCINAA) method has been developed to determine selected elements in various types of cereal and vegetable from Ghana using relatively short-lived nuclides (t1/2<80 s) and the Compton suppression counting. The samples were irradiated for 10 s at the Dalhousie University SLOWPOKE-2 research reactor facility (DUSR) and allowed to decay for 20 s, and counted for 40 s. The process is repeated every 50 s for 4 cycles to quantify Dy, Hf, Rb, Sc and Se through 165mDy, 179Hf, 86mRb, 46mSc, and 77mSe. The detection limits were generally of the order of 1.0 ng g(-1) except for Rb which is about 1 microg g(-1). Both precision and accuracy of the method were found to be good.

Contemporary management of wartime vascular trauma.

OBJECTIVE: The treatment of wartime injuries has led to advances in the diagnosis and treatment of vascular trauma. Recent experience has stimulated a reappraisal of the management of such injuries, specifically assessing the effect of explosive devices on injury patterns and treatment strategies. The objective of this report is to provide a single-institution analysis of injury patterns and management strategies in the care of modern wartime vascular injuries. METHODS: From December 2001 through March 2004, all wartime evacuees evaluated at a single institution were prospectively entered into a database and retrospectively reviewed. Data collected included site, type, and mechanism of vascular injury; associated trauma; type of vascular repair; initial outcome; occult injury; amputation rate; and complication. Liberal application of arteriography was used to assess these injuries. The results of that diagnostic and therapeutic approach, particularly as it related to the care of the blast-injured patient, are reviewed. RESULTS: Of 3057 soldiers evacuated for medical evaluation, 1524 (50%) sustained battle injuries. Known or suspected vascular injuries occurred in 107 (7%) patients, and these patients comprised the study group. Sixty-eight (64%) patients were wounded by explosive devices, 27 (25%) were wounded by gunshots, and 12 (11%) experienced blunt traumatic injury. The majority of injuries (59/66 [88%]) occurred in the extremities. Nearly half (48/107) of the patients underwent vascular repair in a forward hospital in Iraq or Afghanistan. Twenty-eight (26%) required additional operative intervention on arrival in the United States. Vascular injuries were associated with bony fracture in 37% of soldiers. Twenty-one of the 107 had a primary amputation performed before evacuation. Amputation after vascular repair occurred in 8 patients. Of those, 5 had mangled extremities associated with contaminated wounds and infected grafts. Sixty-seven (63%) patients underwent diagnostic angiography. The most common indication was mechanism of injury (42%), followed by abnormal examination (33%), operative planning (18%), or evaluation of a repair (7%). CONCLUSIONS: This interim report represents the largest analysis of US military vascular injuries in more than 30 years. Wounding patterns reflect past experience with a high percentage of extremity injuries. Management of arterial repair with autologous vein graft remains the treatment of choice. Repairs in contaminated wound beds should be avoided. An increase in injuries from improvised explosive devices in modern conflict warrants the more liberal application of contrast arteriography. Endovascular techniques have advanced the contemporary management and proved valuable in the treatment of select wartime vascular injuries.

The endovascular management of recurrent aortic hypoplasia and coarctation in a 15-year-old male.

A 15-year-old male complained of easy fatigability, leg weakness, and pain on exertion with episodes of syncope while playing baseball. His past medical history was significant for aortic coarctation associated with a congenital bovine hypoplastic aortic arch. A recent arteriogram revealed innominate and left common carotid artery stenosis as well as recurrent coarctation. He had previously undergone three Dacron patch aortoplasties. At the age of 7, he underwent a fourth operation for recurrent coarctation and because of extensive scar tissue in the region of his prior procedures, a left subclavian artery-to-descending aortic bypass was performed. An endovascular repair to deal with the recent recurrence was performed because of prior surgical difficulties. Percutaneous balloon-expandable stents were placed in the aortic coarctation, innominate, and the left common carotid arteries. Postprocedure, ankle brachial indices were >1 and the patient remains asymptomatic after 1 year.

What imaging studies are necessary for abdominal aortic endograft sizing? A prospective blinded study using conventional computed tomography, aortography, and three-dimensional computed tomography.

OBJECTIVE: Preoperative imaging modalities for endovascular abdominal aortic aneurysm repair (EVAR) include conventional computed tomography (CT), aortography with a marking catheter, and three-dimensional computed tomography (3D CT). Although each technique has advantages, to date no study has compared in a prospective manner the reproducibility of measurements and impact on graft selection of all three modalities. The objective of this study was to determine the most useful imaging studies in planning EVAR. METHODS: Twenty patients being considered for EVAR were enrolled prospectively to undergo a conventional CT scan and aortography. The CT scans were then reconstructed into 3D images using Preview Treatment Planning Software (Medical Media Systems, West Lebanon, NH). Four measurements of diameter and six of length were made from each modality in determining the proper graft for EVAR. RESULTS: Measurements from all three modalities were reproducible with intraobserver correlation coefficients of 0.79 to 1.0 for aortography, 0.87 to 1.0 for CT, and 0.96 to 1.0 for 3D CT. Measurements between observers were also similar from each modality; interobserver correlations were 0.70 to 0.97 for aortography, 0.76 to 0.97 for CT, and 0.73 to 0.99 for 3D CT. Significant differences ( P < .01) in diameter measurements were noted at D2 with aortography compared with 3D CT, whereas differences in length measurements were found between CT and 3D CT at L4 (nonaneurysmal right iliac) ( P < .01). The correlation between CT and 3D CT for most length measurements was acceptable (0.63 to 1.0). Aortography for diameters correlated poorly (0.35 to 0.67) with 3D CT. When the endograft selected by aortography/CT or 3D CT alone was compared with the actual endograft used, there was agreement in 11 of 11 patients when adjusted for +/- one size in diameter or length. CONCLUSION: Reproducible and comparable measures of diameter and length can be obtained by each of three imaging modalities available for endograft sizing. As a single imaging modality, 3D CT appears to have the best correlation for both diameters and lengths; however, the difference is not sufficient enough to alter endograft selection. Three-dimensional CT may be reserved for challenging aortic anatomy where small differences in measurements would affect patient or graft selection for EVAR.

Endovascular assisted in situ bypass grafting: a simplified technique for saphenous vein side branch occlusion.

The in situ bypass procedure for lower extremity limb salvage requires a long continuous incision or multiple interrupted incisions over the greater saphenous vein to ligate the saphenous vein side branches. This can result in wound complications that frequently prolong hospital stay and threaten the graft. In an effort to reduce the incidence of wound complications, alternate methods of occluding the vein side branches have been used. One method is to deliver coils under angioscopic vision into the saphenous vein side branches. This report details a simplified technique that uses widely available catheter-based equipment to perform saphenous vein side branch occlusion under fluoroscopic guidance.

Mesenteric venous thrombosis in a patient with prothrombin 20210A mutation and antithrombin III deficiency: challenges to conventional anticoagulation--a case report.

Mesenteric venous thrombosis presents as vague abdominal pain in patients with a medical or family history suggestive of a hypercoagulable state. Classic computed tomography findings will often confirm the diagnosis, and the presence of persistent abdominal pain or tenderness will determine the need for surgical intervention. Expeditious anticoagulation is the treatment of choice. This case demonstrates the CT findings for mesenteric venous thrombosis and discusses the challenges of anticoagulation in a patient with 2 hypercoagulable disorders.

Correlation between total and EDTA/DTPA-extractable trace elements in soil and wheat.

Wheat and wheat products are more important sources of energy and nutrients in diets of people in many cultures compared to other foods. The daily consumption of wheat is about 200 g/d/person in Western Europe and North America. On the other hand, 400-450 g of wheat and wheat products are consumed daily by average Turkish people. Wheat samples collected from the Iskenderun region in 1995 and 1996 and Ankara and Istanbul regions in 1995 were analyzed for their trace element content by instrumental neutron activation analysis (INAA). In addition, 13 soil samples were collected from the Iskenderun region in 1996. Total soil samples were analyzed by INAA and atomic absorption spectrometry (AAS), EDTA-extractable elements by INAA, and DTPA-extractable elements by AAS. Correlation analysis and enrichment factor calculations were applied to the trace element results. In wheat samples, a strong correlation was found between the elements such as Sc, La, Sm, Rb, and K whose main source is soil. The concentration of Se appeared to show larger variations among different regions. No significant correlation was observed for elements such as As and Se whose main sources in the atmosphere are anthropogenic activities.

Spatial distribution of extractable organohalogens in northern pink shrimp in the north Atlantic.

Extractable organohalogens (EOX) are organic compounds that contain chlorine, bromine and/or iodine, which can be separated from the matrix by liquid/liquid or liquid/solid extraction. A combination of instrumental neutron activation analysis (INAA) and solvent extraction methods has been developed for the determination of EOX from the shrimp Pandalus borealis. Levels of EOX were evaluated for spatial trends for shrimp caught in several areas off the Labrador coast, off the coast of Nova Scotia, and off the coast of Maine. Muscle contained 1.09-6.05 micrograms EOCl/g tissue and 105-498 micrograms extractable organochlorine (EOCl)/g lipid; 0.0607-0.288 microgram extractable organobromine (EOB)r/g tissue and 4.74-10.5 micrograms EOBr/g lipid; and 0.014-0.048 microgram extractable organoiodine (EOI)/g tissue and 1.03-1.76 micrograms EOI/g lipid, respectively. The levels of EOCl in roe were 1.60-12.34 micrograms/g tissue and 39.0-146 micrograms/g lipid. In roe, the EOBr levels were 0.707-1.03 micrograms/g tissue and 6.96-13.5 micrograms/g lipid; and EOI levels were 0.123-0.349 microgram/g tissue and 1.42-4.11 micrograms/g lipid. The EOCl, EOBr, and EOI levels in roe increased noticeably from north to south along the coast of Labrador. Samples taken from the coast of Maine and from Canso Hole were typically higher in EOCl levels than those taken from Labrador. The results for EOBr and EOI were in the same range as those from Labrador.

Determination of selenium in Canadian food items by cyclic instrumental neutron activation analysis.

Instrumental neutron activation analysis (INAA) and pseudocyclic INAA (PCINAA) have been used to determine the selenium content of a variety of Canadian food items. Use of the 162-keV gamma ray of short-lived 77mSe in INAA allowed relatively simple and rapid determinations and was suitable for many of the foods. PCINAA was found to give lower detection limits and was used for the low-selenium food samples. Both internal and external quality assessments were used to evaluate and assure the accuracy and precision of the methods developed.

Extractable organohalogens in tissues of beluga whales from the Canadian Arctic and the St. Lawrence estuary.

Samples of blubber, brain, kidney, liver, and muscle of individual beluga whales were extracted and analyzed for extractable organic Cl (EOCl), Br (EOBr), and I (EOI) by neutron activation analysis. The highest levels of EOCl (554 microg g(-1) lipid) were found in the kidney of Arctic beluga and the lowest (24 microg g(-1) lipid) in the blubber. Levels in brain and liver lipids were on average of equal magnitude. The unequal distribution of EOCl in tissue lipids is in marked contrast to the equal distribution, in lipid, demonstrated for organochlorines such as DDTs and PCBs by a number of investigations. The distribution of brominated (EOBr) and iodinated (EOI) compounds was similar and markedly different from that of EOCl. The tissue distribution of EOCl seems to be related to the proportion to polar lipids in the tissues. Beluga from St. Lawrence had significantly higher brain EOCl levels than the Arctic samples whereas the levels of EOCl in liver and kidney were higher in the Arctic whales.

Trace element contents in food determined by neutron activation analysis and other techniques.

Advances in analytical methodology and sophisticated instrumentation introduced during the last few decades have not only helped to recognize the presence of a large number of essential and toxic trace elements in biological materials and food stuffs, but also added a new dimension in our understanding of their role in health and disease. In deficiency states, most essential trace elements cause health problems. The trace element problem as a public health issue has a very low priority in developing countries. Daily dietary intake data based on well-conducted studies are limited in many parts of the world. The present authors are in the process of generating data for the intake levels of a number of major and minor inorganic elements both in developed and developing countries. The results so far obtained show wide variations. The intake levels of several elements, including potassium, magnesium, zinc, copper, and selenium, are below the current recommended levels. The concentration of toxic metals, such as aluminum, cadmium, lead, and mercury, are within acceptable limits in most of the diets analyzed.

Determination of nanogram amounts of iodine in foods by radiochemical neutron activation analysis.

Three different neutron activation analysis methods have been developed for the determination of ppb levels of iodine in food samples. The methods are based on the separation of iodine using (i) toluene extraction followed by bismuth sulfide coprecipitation; (ii) bismuth sulfide coprecipitation followed by radiochemical purification with palladium iodide; and (iii) radiochemical isolation by bismuth sulfide coprecipitation. The accuracy of these methods was evaluated by analysing replicate samples of reference materials. The measured values of iodine in A-11 Milk Powder, H-4 Animal Muscle and H-9 Mixed Human Diet from the International Atomic Energy Agency (IAEA) are statistically indistinguishable from the IAEA recommended values, and those for the Standard Reference Materials 1571 Orchard Leaves and 1577 Bovine Liver from the National Institute of Standards and Technology (NIST) are in good agreement with the NIST information values. The precision, in terms of relative standard deviation, is 5% at 50-100 ppb and 10% at 5-20 ppb levels of iodine. The absolute detection limits of these methods vary between 0.5 and 10 ng of iodine. All three methods were used to measure the iodine content of several food samples. The method involving bismuth sulfide coprecipitation followed by radiochemical purification provides the best detection limit and highest precision.

Total organochlorine content of fish from the Great Lakes.

Residues of polychlorinated biphenyls (PCBs) and organochlorine pesticides were determined in several species of commercial fish from the Great Lakes and compared to the total organic chlorine determined by neutron activation analysis. The mean organochlorine contents ranged from 44 to 138 ppm (lipid basis) and were 5 to 72 times higher than the contents of PCBs and organochlorine pesticides. Marine fish also contained a large proportion of unidentified organic chlorine. The unknown material in the Great Lakes fish was found to chromatograph with the high molecular weight lipid fraction by gel permeation chromatography.

Microwave acid digestion and preconcentration neutron activation analysis of biological and diet samples for iodine.

A simple preconcentration neutron activation analysis (PNAA) method has been developed for the determination of low levels of iodine in biological and nutritional materials. The method involves dissolution of the samples by microwave digestion in the presence of acids in closed Teflon bombs and preconcentration of total iodine, after reduction to iodide with hydrazine sulfate, by coprecipitation with bismuth sulfide. The effects of different factors such as acidity, time for complete precipitation, and concentrations of bismuth, sulfide, and diverse ions on the quantitative recovery of iodide have been studied. The absolute detection limit of the PNAA method is 5 ng of iodine. Precision of measurement, expressed in terms of relative standard deviation, is about 5% at 100 ppb and 10% at 20 ppb levels of iodine. The PNAA method has been applied to several biological reference materials and total diet samples.

Studies on zinc- and cadmium-bound proteins in bovine kidneys by biochemical and neutron activation techniques.

Bovine kidneys were found to contain about 78 ppm Zn and 0.78 ppm Cd. Approximately 45% of Zn and 60% of Cd were present in the cytosol fraction. More than 95% of these two metals were bound to macromolecules. Both Zn- and Cd-protein complexes were observed to be stable between pH 7 and 10.5. Separation and characterization of these proteins were carried out using several chromatographic and electrophoretic techniques in conjunction with instrumental neutron activation analysis (INAA). The results showed the presence of at least four Zn-binding proteins with mol wt greater than 300,000, 260,000, 89,000, and 27,000 and at least three Cd-binding proteins of mol wt greater than 300,000, 32,000, and 13,000.

Metabolic deposition of selenium and cadmium into the hair and other tissues of the guinea pig.

To better understand the significance of hair trace-element measurements and their relationships with the trace-element levels in body organs and fluids, a series of controlled animal experiments were conducted in which several trace elements were periodically measured during a 90-day chronic exposure to selenium and cadmium. Chronic selenium exposure appeared to be reflected by elevated selenium levels in the hair, kidneys, and liver. Chronic cadmium exposure, although reflected by kidney and liver elevation, appeared not to be reflected by corresponding increases in its concentration in the hair.